Air fresheners are a familiar product used both industrially and domestically to modify the olfactory properties of an enclosed atmosphere. Some of these fresheners are designed to remove undesired odors from the atmosphere, while others add desired odors.
Several types of fresheners have been developed in the latter category of odor-dispensing units. One type employs a can of a solid or liquid aromatic agent, placed in a housing mounted in the space to be freshened. Dispersal of the fragrance can be allowed to occur passively by movement of air within the space past the exposed agent. Alternatively, the housing may be equipped with a fan or similar means for promoting dispersal. Once the agent is exhausted, the can or other container is discarded and a refill can is emplaced.
These containers have significant drawbacks for certain markets. The agent itself can be a messy substance, especially in its liquid form. It therefore requires the exercise of considerable caution to avoid spillage or other mishaps. In addition, the aromatic agent in these dispensers evaporates quickly, so that large containers, and hence cumbersome housings, are required if the supply is to last for any significant period of time.
To meet the demand for a compact, easily handled product, fragrance cartridges were developed. The cartridges use pads treated with an odoriferous agent and mounted in a housing of convenient size. Like the aromatic agent containers, cartridges are made for a single usage, after which they are discarded.
One construction for these cartridges which is known in the art uses a pad treated with an aromatic agent and placed in a trough-like housing. The open top of the housing is sealed with a permeable material that allows dispersal of the fragrance.
Cartridge-type air fresheners have advantages over their more cumbersome counterparts described earlier, in terms of convenience, neatness and the like. However, known cartridge-type fresheners have until now been unreliable in terms of their ability to dispense a sufficiently strong aroma for a significant length of time. Generally, such cartridges are effective only for about 2 weeks or less. This is largely due to the fact that the fragrant agent is released too quickly through the permeable material. In designing cartridge dispensers, it has therefore become a primary concern to balance the properties of dispersal rate and cartridge life.
It is therefore an object of this invention to provide a convenient, cartridge-type air freshener that has a long life.
It is a further object of this invention to provide such an air freshener that releases an aroma at a rate adequate to conventional applications.
It is another object of the invention to provide a method of making such cartridges that yields products having predetermined, desired properties of life and release rate.